We report the case of a 68-year-old woman with refractory diffuse large-B-cell lymphoma (DLBCL), germinal-center subtype, with a BCL2 rearrangement and multiple copies of MYC and BCL6. Her disease was refractory to intensive infusional chemotherapy, dose-adjusted etoposide, doxorubicin, and cyclophosphamide with vincristine and prednisone plus rituximab (DA-EPOCH-R), and then to four additional lines of therapy, including intermediate-intensity allogeneic stem-cell transplantation from an 8/8 HLA-matched unrelated donor. She enrolled in a clinical trial of JCAR017 (ClinicalTrials.gov number, NCT02631044), a CD19-directed chimeric antigen receptor (CAR) T-cell product.